How to complete Tunnel Geometry ("extendtosymmetryaxis" and "symmetricclose" command).

Dear Stefanos and Team, 

I am using Plaxis 2D V21. I am currently trying to re-do Tutorial 7 (Excav. of an NATM Tunnel) through Python remote scripting. I would like to perform the "extendtosymmetryaxis" and "symmetricclose"  command through python. The command line looks like the following:

Normally, I would expect the python script to look like:

--------------------------------------------------------------------------

        g_i.extendtosymmetryaxis(g_i.Tunnel_1.CrossSection)
        g_i.symmetricclose(g_i.Tunnel_1.CrossSection)

--------------------------------------------------------------------------

However, I got an "AttributeError: Requested attribute 'extendtosymmetryaxis' is not present" error. I also can't find the commands in scripting or command reference (from the Help menu). Is there a way to do this through remote scripting? or is there a reference/manual that I overlook?

Thank you very much for your time and attention. 

Kind regards,

M. Rayyan